Modern computer networks deployed in large installations (e.g., datacenters, offices, universities, etc.) may be complex and dynamic, with a large number of end-user computers being continually added, removed, and moved between different physical locations (e.g., from one room, floor, or building to another). Such networks are predominantly Ethernet-based, using copper wiring (e.g., category 5 (“Cat5”) cable or category 7 (“Cat7”) cable) or fiber-optic cables running between network elements. Communications cabinets or rooms are often deployed with patch panels in order to facilitate installation and modification of network connections.
In certain situations a network administrator needs to physically locate a particular device that is connected to the network. For example, hundreds or thousands of devices may be located in a large datacenter and, at any given time, one or more of these devices may fail and need to be located by the network administrator so that it can be replaced or fixed. As another example, the network administrator may need to locate a computer that is functioning in a way that negatively impacts network functionality (e.g., by transmitting spurious data across the network). As yet another example, the network administrator may need to locate a computer that is being intentionally or unintentionally misused by a user in a way that may endanger valuable information assets. In such cases, the network administrator will need to quickly determine the physical location of the computer or other device in question. Information sufficient to determine the physical location of the device for this purpose may be the room number in which the offending computer resides, and preferably the identification of a physical receptacle on a wall within that room. For reasons that will be described presently, mere identification of the physical layer address or network layer address (a.k.a., “network address”) of the device in question will generally not convey information sufficient for this purpose.
Conventional network monitoring equipment can determine a device's network address (e.g., an Internet protocol (“IP”) address) and physical layer address (e.g., an Ethernet Media Access Control (“MAC”) address) from protocol data units (“PDU”s) transmitted by the device. As used herein the term protocol data unit means data in a format specified by a protocol, which data includes a header containing protocol control information (e.g., address information for routing the protocol data unit) and possibly a data portion containing application data or another protocol data unit. However, this information does not directly reveal the precise physical location of a device. This lapse can be rectified by manually maintaining a wiring diagram that depicts the network topology (i.e. the physical interconnections between the various network elements), along with the addresses and physical locations of all devices. In order to maintain an accurate wiring diagram, entries must be added to the wiring diagram whenever a new device is added to the network, entries must be deleted when devices are removed from service, and entries must be modified every time a device is moved to a different location. Such manual maintenance of the wiring diagram will of necessity be labor-intensive and error-prone, and updating of the wiring diagram is often postponed or neglected. Furthermore, end users may frequently move computers between physical locations without notifying the network administrator, frustrating an administrator's best efforts to maintain an accurate wiring database.
One proposed solution to these problems is to automatically determine network topology information (e.g., information related to the logical and/or physical interconnections between network elements). Determining network topology information can be achieved using standard software utilities (e.g., the ‘traceroute’ command from the IP suite), special-purpose protocols, management layer functions, software, and possibly additional network hardware. However, the automatically determined network topology information does not completely specify the physical location of a device. For large networks (e.g., hundreds or thousands of devices), mere network topology information will usually be insufficient for determination of physical location.
Other proposed solutions may incorporate new active network elements, such as intelligent patch panels that can be interrogated via the network by the network administrator, or configuring devices to report their physical locations using the Global Positioning System (“GPS”). These solutions add undesirable expense and complexity to the infrastructure of wired networks. Furthermore, because the use of these additional devices is not standardized, implementing these solutions may require extensive software development and integration.